1. Field of the Invention
The present invention relates to a photosensitive resin which includes, in the structure thereof, a moiety that readily generates an acid through irradiation with active radiation (e.g., deep UV rays, electron beams, X-rays, or EUVs (extreme ultraviolet rays) and an acid-dissociable group, and which is useful as a chemically amplified photoresist material; and to a photosensitive composition containing the photosensitive resin.
2. Background Art
Semiconductor devices; for example, highly integrated circuit elements such as DRAM, have been required to have higher density, higher degree of integration, or higher operational speed. Accordingly, in the field of production of various electronic devices, keen demand has arisen for establishment of a half-micron-order micro-fabrication technique; for example, development of a photolithographic technique for micro-patterning. In photolithography, one means for micro-patterning is employment of active radiation (exposure light) of short wavelength for photoresist patterning. In a demagnification projection aligner, resolution (R) is represented by Rayleigh's equation: R=k·λ/NA (wherein λ represents the wavelength of exposure light, NA represents the numerical aperture of a lens, and k represents a process factor), and therefore, resolution can be enhanced by reducing the wavelength λ of active radiation (exposure light) employed for resist patterning.
Chemically amplified photoresists have been proposed as being suitable for use in light of short wavelength (see, for example, Patent Document 1). A characteristic feature of a chemically amplified photoresist resides in that a protonic acid is generated from a photoacid generator (i.e., a component of the photoresist) through irradiation with exposure light, and, through thermal treatment following light exposure, the protonic acid catalytically reacts with, for example, a polymer having an acid-dissociable group (i.e., a group that is dissociated/degraded by an acid). Most currently developed photoresists are of a chemically amplified type. A variety of sulfonium salts have been known as photoacid generators for use in such a chemically amplified photoresist.
However, such a conventional sulfonium salt photoacid generator poses a problem in that, for example, it has poor compatibility with a polymer having an acid-dissociable group, the polymer being a primary component of a photoresist. Needless to say, such a problem adversely affects a patterning process; for example, when a photoresist containing a sulfonium salt photoacid generator is exposed to active radiation for patterning, the thus-formed pattern may fail to attain a predetermined shape.
[Patent Document 1]
U.S. Pat. No. 4,491,628